1. Field of the Invention
The present invention relates to a signal processing device for correcting the output signal level difference between each divided region when an imaging region of an imaging element in a digital camera, for example, is divided into a plurality of regions in the left and right directions, and a process of simultaneously reading the data for each divided region and combining the data is performed.
2. Description of the Related Art
In a digital camera, a 2ch CCD with a device configuration of 2-output type in which the CCD is divided into two left and right regions and the respective signal is output is being developed to improve the read-out speed of the CCD when taking moving image or when taking rapid serial pictures.
In the 2ch CCD, due to the precision difference of a CDS/AGC circuit arranged for each left and right imaging region, the left and right output signals do not match. Further, even if means for matching the left and right output signals in a fixed manner is provided, the possibility of the temperature characteristic and the like of the left and right CDS/AGC circuits being the same is low, and thus matching the left and right output signal levels is difficult.
As a method of correcting the output signal level difference between the channels, a method of imaging a planar image by emitting LED on the inner side of the shutter with the shutter in a closed state before photographing, measuring the signal level difference between the channels of the CCD, and correcting the signal level difference between the channels of the CCD has already been developed. However, although this method is effective in intermittent photographing such as when taking a still image, an appropriate correction can not be performed when performing continuous photographing as when taking a moving image or when the output signal level difference between the channels changes by the temperature rise while photographing.